A conventional arrangement is described in German Patent 38 12 633 A1 in which a rotary transformer is used, for example, for transmitting signals between a controller and an airbag installed in the steering wheel of a vehicle. The operability of an airbag must be constantly monitored to ensure that it is ready for use in any emergency situation, so the resistance of the squib, which should typically be between 1.8 Ohm to 2.5 Ohm, is subjected to periodic measurement. In the conventional arrangement, the signal transmission between the controller and the airbag using inductively coupled coils of the rotary transformer depends on the distance between the two coils, i.e., the size of the air gap between the pot-type cores of the coils. Consequently, assembly and manufacturing tolerances of the steering wheel, in which the secondary pot-type core of the rotary transformer is installed, may result in distortions of the measured resistance of the squib. In order to avoid such distortions, the aforementioned background art provides an oscillator circuit on the secondary side of the rotary transformer, which is excited by a control signal from the primary side. After the control signal is turned off, the decay of the response signal of the oscillator circuit is retransmitted to the primary side and the resistance on the secondary side is calculated from the decaying response signal.